TAMPA — Yankees pitcher Joba Chamberlain could be lost for the season after suffering a gruesome ankle injury Thursday that general manager Brian Cashman called “very significant.”

The right-handed reliever had surgery Thursday at St. Joseph’s Hospital and will remain there for at least the next few days after undergoing an MRI exam and CT scan yesterday to determine the severity of the injury — which Cashman described as an open dislocation of the right ankle, meaning the bone broke through the skin.

The accident occurred while Chamberlain, 26, played with his 5-year-old son, Karter, at a children’s play place. Karter was not injured.

Cashman refused to put a timetable on Chamberlain’s return and said of the injury potentially ending Chamberlain’s career: “I’m not in a position to say,” adding later, “I’d like to say no. My heart and my gut tells me no.”

Though Chamberlain lost a considerable amount of blood and paramedics were called to the scene, both a Yankees source and the pitcher’s agent denied that his life was ever in danger.

Chamberlain’s father, Harlan, told The Post reports that his son’s life was in danger were untrue.

“That’s [B.S.],” he said.

As for how the injury happened, Cashman said, “I believe it was a trampoline. Whether it was a trampoline specifically [I don’t know]. … There are places out there you can go with your children and it’s just basically a lot of gymnastic stuff. That is a loose description because I’m hearing this third-hand.’’

A team source said Chamberlain and his son were at a place where you sign a waiver and the entire floor is a trampoline.

This is a major setback for Chamberlain, who was ahead of schedule in his comeback from Tommy John surgery last June.

“We thought it was realistic to get him back around June,” manager Joe Girardi said. “I don’t think that’s so realistic now. It’s a power arm that was going to come back strong.”

Chamberlain has a non-guaranteed contract that pays him $1.675 million this year. Asked if this falls in the category of unacceptable off-the-field injuries, Girardi said, “I don’t want to get into that now. What I want to talk about is getting him better and being there for this kid. He’s going through a lot.”

Girardi said he spent about 30 minutes with Chamberlain yesterday.

“I wanted to see how he was doing,” the manager said. “You know it’s crushing. I just told him, ‘We’re going to be here for him. We’re going to get you through this, and we’re going to get you back on the mound. But you’re going to go through some difficult times…’ You can see the disappointment, there’s no doubt [about] that.”

Dr. Andrew Brief, a surgeon specializing in foot and ankle surgery with Ridgewood Orthopedic Group in New Jersey, called it “a pretty devastating injury” and that “it would be hard to imagine’’ Chamberlain returning in fewer than four months.

According to Brief, because the ankle ligaments were completely torn through, it likely will be six weeks to three months before Chamberlain can do any weight-bearing activity.

That includes not being able to rehab from last year’s elbow surgery, so that schedule will be thrown off.

Those factors make it a distinct possibility Chamberlain won’t be back with the Yankees in 2012 and perhaps not at all.

“I feel extremely bad for him,” said Derek Jeter, who spoke to Chamberlain yesterday. “He worked hard to get his arm back in shape and to have some fluke accident happen. … I’m pretty sure how he’s feeling. He’s got to be disappointed.”

“I know how much he loves the game and was looking forward to coming back,” Cashman said. “This was an unfortunate accident that has clearly derailed that. What more does that mean? I don’t know.”